In the modern manufacturing industry, it is a well recognized problem that there is a potential for the adherence and buildup of a variety of foreign substances on the inner surface of fluid transport system pipes. Manufacturing facilities and other processes which require the use of a particular fluid medium, such as fresh water, have sought a method to keep the fluid transport system operational and free of any foreign organisms or debris.
One such foreign organism of particular concern is known as Zebra Mollusks better known as Zebra Mussels See, for example, an article published in the December 1990 issue of "Electrical World" pages 72-74 and an article published in the Jul. 1990 issue of "The Atlantic Monthly" on pages 81-87. The contents of these articles are incorporated herein by reference thereto.
When the fluid transport systems of current technology exhibit diminished capacity due to clogging by foreign substance buildup, one method of servicing a submerged piping system would be to have a person use a dragging device to pull through the fluid transport system to dislodge the buildups or clogs and subsequently pull them through to the exit for manual cleanup. Drawbacks to this method are apparent and would include the fact that it is not only labor-intensive but time-consuming. Also this method cannot be accomplished continuously, but must be done on a scheduled basis.
Another possible cleaning method used for facilities, such as water treatment plants, includes flushing the fluid transport system with large quantities of chemicals such as chlorine or potassium permanganate. While this process can be conducted continuously, it is not efficient or cost-effective to induce large quantities of chemicals into the desired fluid medium which must later be separated out.
As discussed in the above-referenced articles, three types of problems have been identified with Zebra-Mussel fouling in water systems. Initially, layers of attached mussels will reduce or block flow, even through large-diameter piping trash racks, and traveling screens. Eventually, shells or clumps of shells breaking free of their attachment will block openings in piping, heat exchangers, strainers, or traveling screens. Finally, attachment points accumulate other debris and serve as sites for corrosion. There are three EPA-approved chemical methods that have been tried in US powerplants-chlorination, the most discussed method; bromination, primarily Acti-brom, a Nalco Chemical Co (Naperville, Ill.) product; and Betz Laboratories' (Trevose, Pa) Clam-trol. Several Other chemical treatments have been tried in laboratory tests, but not in a utility environment. Chlorination is the most common chemical control for zebra-mussel fouling. Continuous chlorination at 0.3 ppm for up to three weeks is required to achieve efficacy. Intermittent chlorination programs, that feed a few hours daily are ineffective. Using other chemicals-such as ozone, hydrogen peroxide, and potassium permangenate is possible, but expensive, environmentally unsound, and/or impractical to distribute throughout a cooling system. It has been reported that Detroit Edison is trying to control mussels by scraping and hydroblasting during regular maintenance. Janiece Romstadt has received federal permission to use a commercial mollucicide. Ontario Hydro is treating some of its coolant with hypochlorite, an oxidant that chews away at the soft parts of the organism and is the active ingredient in household bleach; the utility admits, however, that this short-term solution is offensive to a public anxious about the environment. One alternative is ozonation. Like hypochlorite, ozone is an oxidant; it is also environmentally benign. But it is extremely expensive. Ontario Hydro estimates that ozonation would cost it $9 million per plant. John Stanley, of the U.S. Fish and Wildlife Service, puts the bill for re-engineering, maintenance, and other forms of mussel abatement at almost half a billion dollars a year. But none of the emergency measures, though they may alleviate specific problems here and there, will do anything to halt the overall proliferation of Zebra Mussels. The mussels are very strongly byssate and they will attach to insides and occlude the openings of industrial and domestic pipelines, clog underground irrigation systems of farms, greenhouses, and any other facility that draws water directly from the Great Lakes, encrust navigation buoys to the point of submerging them, and encrust hulls of boats and other types of sailing craft that remain in the water over the summer and fall. . . . The mussels may also become a significant vector of parasites that are lethal to game species of waterfowl and fish.
In the November 1991 issue of "Underwater USA" a news article appeared which indicated that, the tiny but dreaded Zebra Mussel has been discovered for the first time in a section of the Mississippi River near La Crosse, Wis., a U.S. Fish and Wildlife Service toxicologist reports.
Leif Marking says he expects to see the Zebra Mussel population explode by next year. Worse, it's likely boaters will inadvertently introduce the Zebra Mussels to Minnesota lakes.
The mussels have an extremely hard shell and clog water intakes at power plants and municipal water systems.
The Monroe, Mich., water supply was crippled for three days when the mussels clogged an intake pipe. Water bills increased percent to pay for removing them.
An Ontario electric company spent $10 million on chlorine to keep the mussels out of power plant water intake pipes.
Marking expects the same things to happen at power and water plants on the Mississippi. He says locks and dams also are favored by the mussels, which cause leaks and prevent gates from closing completely.
Therefore, it is apparent that it is desirable to create a fluid transport system in which the pipes are manufactured or lined with a material which would substantially minimize the initial adherence and eventual buildup of foreign substances on the inner surfaces of the pipes while submerged in a fluid medium.